From: Eyal Birger

On 64 bit systems, struct bt_skb_cb size is padded by 6 bytes in order
to reach 8 byte alignment.
Convert boolean fields force_active, incoming and req_start to bit fields
in order to eliminate the padding.

...

...

 struct bt_skb_cb {
 	__u8 pkt_type;
-	__u8 incoming;
 	__u16 opcode;
 	__u16 expect;
-	__u8 force_active;
-	bool req_start;
+	__u8 force_active:1;
+	__u8 incoming:1;
+	__u8 req_start:1;
 	u8 req_event;
 	hci_req_complete_t req_complete;
 	struct l2cap_chan *chan;

You've generated some pad bytes, best to put everything on its natural alignment.
The old version had req_complete at offset 9, the new one at offset 8.
Not sure how this removes 6 bytes of pad.

	David